title: PACAP modulates GnRH signaling in gonadotropes.
abstract: Hypothalamic gonadotropin-releasing hormone is known to be critical for normal gonadotropin biosynthesis and secretion by the gonadotrope cells of the anterior pituitary gland. Additional regulation is provided by gonadal steroid feedback as well as by intrapituitary factors, such as activin and follistatin. Less well-appreciated is the role of pituitary adenylate-cyclase activating polypeptide (PACAP) as both a hypothalamic-pituitary releasing factor as well as an autocrine-paracrine factor within the pituitary. PACAP regulates gonadotropin expression alone and through modulation of GnRH responsiveness achieved by increases in GnRH receptor expression and interactions at the level of intracellular signaling pathways. In addition to direct effects on the gonadotrope, PACAP stimulates follistatin secretion by the folliculostellate cells and thereby contributes to differential expression of the gonadotropin subunits. Conversely, GnRH augments the ability of PACAP to regulate gonadotrope function by increasing pituitary PACAP and PACAP receptor expression. This review will summarize the current understanding of the mechanisms by which PACAP modulates gonadotrope function, with a focus on interactions with GnRH.
authors.affiliation: Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9032, United States. Electronic address: lisa.halvorson@utsouthwestern.edu.
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Halvorson
mesh_terms: D000818:Animals; D019898:Autocrine Communication / Q000502:physiology; D038681:Follistatin / Q000096:biosynthesis; D005786:Gene Expression Regulation / Q000502:physiology; D052681:Gonadotrophs / Q000166:cytology / Q000378:metabolism*; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D006801:Humans; D019899:Paracrine Communication / Q000502:physiology; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide / Q000378:metabolism*; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide / Q000096:biosynthesis; D015398:Signal Transduction / Q000502:physiology*
chemical_list: C495401:ADCYAP1 protein, human; D038681:Follistatin; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D051236:Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide; D007987:Gonadotropin-Releasing Hormone
keywords: GnRH; GnRH receptor; Gonadotropin; PACAP; PACAP receptor